import { BaseCommand, flags } from '@adonisjs/core/ace'
import type { CommandOptions } from '@adonisjs/core/types/ace'
import { Worker } from 'bullmq'
import queueConfig from '#config/queue'
import { RunDownloadJob } from '#jobs/run_download_job'
import { DownloadModelJob } from '#jobs/download_model_job'
import { RunBenchmarkJob } from '#jobs/run_benchmark_job'
import { EmbedFileJob } from '#jobs/embed_file_job'
import { CheckUpdateJob } from '#jobs/check_update_job'
import { CheckServiceUpdatesJob } from '#jobs/check_service_updates_job'

export default class QueueWork extends BaseCommand {
  static commandName = 'queue:work'
  static description = 'Start processing jobs from the queue'

  @flags.string({ description: 'Queue name to process' })
  declare queue: string

  @flags.boolean({ description: 'Process all queues automatically' })
  declare all: boolean

  static options: CommandOptions = {
    startApp: true,
    staysAlive: true,
  }

  async run() {
    // Validate that either --queue or --all is provided
    if (!this.queue && !this.all) {
      this.logger.error('You must specify either --queue=<name> or --all')
      process.exit(1)
    }

    if (this.queue && this.all) {
      this.logger.error('Cannot specify both --queue and --all flags')
      process.exit(1)
    }

    const [jobHandlers, allQueues] = await this.loadJobHandlers()

    // Determine which queues to process
    const queuesToProcess = this.all ? Array.from(allQueues.values()) : [this.queue]

    this.logger.info(`Starting workers for queues: ${queuesToProcess.join(', ')}`)

    const workers: Worker[] = []

    // Create a worker for each queue
    for (const queueName of queuesToProcess) {
      const worker = new Worker(
        queueName,
        async (job) => {
          this.logger.info(`[${queueName}] Processing job: ${job.id} of type: ${job.name}`)
          const jobHandler = jobHandlers.get(job.name)
          if (!jobHandler) {
            throw new Error(`No handler found for job: ${job.name}`)
          }

          return await jobHandler.handle(job)
        },
        {
          connection: queueConfig.connection,
          concurrency: this.getConcurrencyForQueue(queueName),
          lockDuration: 300000,
          autorun: true,
        }
      )

      // Required to prevent Node from treating BullMQ internal errors as unhandled
      // EventEmitter errors that crash the process.
      worker.on('error', (err) => {
        this.logger.error(`[${queueName}] Worker error: ${err.message}`)
      })

      worker.on('failed', async (job, err) => {
        this.logger.error(`[${queueName}] Job failed: ${job?.id}, Error: ${err.message}`)

        // If this was a Wikipedia download, mark it as failed in the DB
        if (job?.data?.filetype === 'zim' && job?.data?.url?.includes('wikipedia_en_')) {
          try {
            const { DockerService } = await import('#services/docker_service')
            const { ZimService } = await import('#services/zim_service')
            const dockerService = new DockerService()
            const zimService = new ZimService(dockerService)
            await zimService.onWikipediaDownloadComplete(job.data.url, false)
          } catch (e: any) {
            this.logger.error(
              `[${queueName}] Failed to update Wikipedia status: ${e.message}`
            )
          }
        }
      })

      worker.on('completed', (job) => {
        this.logger.info(`[${queueName}] Job completed: ${job.id}`)
      })

      workers.push(worker)
      this.logger.info(`Worker started for queue: ${queueName}`)
    }

    // Schedule nightly update checks (idempotent, will persist over restarts)
    await CheckUpdateJob.scheduleNightly()
    await CheckServiceUpdatesJob.scheduleNightly()

    // Safety net: log unhandled rejections instead of crashing the worker process.
    // Individual job errors are already caught by BullMQ; this catches anything that
    // escapes (e.g. a fire-and-forget promise in a callback that rejects unexpectedly).
    process.on('unhandledRejection', (reason) => {
      this.logger.error(
        `Unhandled promise rejection in worker process: ${reason instanceof Error ? reason.message : String(reason)}`
      )
    })

    // Graceful shutdown for all workers
    process.on('SIGTERM', async () => {
      this.logger.info('SIGTERM received. Shutting down workers...')
      await Promise.all(workers.map((worker) => worker.close()))
      this.logger.info('All workers shut down gracefully.')
      process.exit(0)
    })
  }

  private async loadJobHandlers(): Promise<[Map<string, any>, Map<string, string>]> {
    const handlers = new Map<string, any>()
    const queues = new Map<string, string>()

    handlers.set(RunDownloadJob.key, new RunDownloadJob())
    handlers.set(DownloadModelJob.key, new DownloadModelJob())
    handlers.set(RunBenchmarkJob.key, new RunBenchmarkJob())
    handlers.set(EmbedFileJob.key, new EmbedFileJob())
    handlers.set(CheckUpdateJob.key, new CheckUpdateJob())
    handlers.set(CheckServiceUpdatesJob.key, new CheckServiceUpdatesJob())

    queues.set(RunDownloadJob.key, RunDownloadJob.queue)
    queues.set(DownloadModelJob.key, DownloadModelJob.queue)
    queues.set(RunBenchmarkJob.key, RunBenchmarkJob.queue)
    queues.set(EmbedFileJob.key, EmbedFileJob.queue)
    queues.set(CheckUpdateJob.key, CheckUpdateJob.queue)
    queues.set(CheckServiceUpdatesJob.key, CheckServiceUpdatesJob.queue)

    return [handlers, queues]
  }

  /**
   * Get concurrency setting for a specific queue
   * Can be customized per queue based on workload characteristics
   */
  private getConcurrencyForQueue(queueName: string): number {
    const concurrencyMap: Record<string, number> = {
      [RunDownloadJob.queue]: 3,
      [DownloadModelJob.queue]: 2, // Lower concurrency for resource-intensive model downloads
      [RunBenchmarkJob.queue]: 1, // Run benchmarks one at a time for accurate results
      [EmbedFileJob.queue]: 2, // Lower concurrency for embedding jobs, can be resource intensive
      [CheckUpdateJob.queue]: 1, // No need to run more than one update check at a time
      default: 3,
    }

    return concurrencyMap[queueName] || concurrencyMap.default
  }
}